Brain sites will continue to be mapped in sheep at which electrical stimulation causes either an increase or a decrease in plasma concentrations of PRL, GH or LH. The relationship between hormone changes and autonomic nervous changes induced by brain stimulation will also be studied. Brain sites identified as important regulators of a particular pituitary hormone will be subjected in other sheep to recording of multi-unit activity (MUA) during spontaneous discharges of that hormone. We would hope to observe unique patterns of MUA at fixed times either before, during or after hormones discharges. We will continue our efforts to sample blood from the head with a method which gives concentrations of pituitary and hypophysiotrophic hormones which exceed those in the peripheral circulation.